Dakota Wood, a military analyst at the Center for Strategic and Budgetary Assessments, told the newspaper the figures demonstrate the limits of airstrikes against a resilient insurgency and indicate why more ground troops are needed to provide security in the country.

U.S. President Barack Obama has so far this year has ordered 21,000 more troops to Afghanistan to help battle Taliban militants.

"The Taliban have been able to regain their footing due to the lack of U.S. and coalition forces being present on the ground and the lack of any meaningful Afghan capability in its local police force or national military forces," Wood told USA Today.

Airstrikes have also fallen out of favor as coalition commanders worry about backlash caused from the deaths of innocent bystanders being used a human shields, the newspaper said.